Safety device for gas conduits



Aug. 30, 1932. Vr. MANQIAMELI 1,874,019V

SAFETY DEVICE FOR GAS CONDUITS Filed March 28, 1950 Patented Aug. 30,1932 UNITED STATES PATENT oFFlcE SAFETY DEVICE FOR GAS CONDUITSApplication illed. March 28, 1930, Serial No.

The invention relates to safety devices for protecting gas lines fromback flow and the effect of back fire, such as are liable to occur 1nmains or pipes supplying gas to cutting 5 or welding torches, of whichthe Oxy-acetylene torch is an example, and the invention involves theapplication of a diaphragm actuated valve interposed in a supplyconduit, normally held open by the predominant pres- 4sure in the mainand moved by the diaphragm to close position, when the pressure on thedelivery side of the valve, due to back How, predominates, said valvebeing associated with a piston valve and valve chamber in# terposed inthe line, said valve being held in open position by a frangible supportwhich' Iis ruptured when high pressure, dueto back fire, is imposed onthe piston valve, causing the -latter to close, thereby shutting oif thegas supply in the conduit until the piston valve is removed, refittedwith a frangible support and replaced in its chamber.

The invention is illustrated in the accompanying drawing, in which thefigure is a vertical sectional elevation of the safety device.

In its preferred construction, the device includes a generallycylindrical hollow casting n comprising a lower chamber a and an upperchamber b having open ends closed by suitable screw caps. The saidcasting is provided near its top with tubular extensions e, e and nearits bottom with tubular extenslons Z, Z', the extension Z beingconnected to a source of supply of the gas, the extension e beingconnected to an instrument, such as a blow torch, with which the gas isemployed and the extensions Z and a are con- 4 nected by a coil orrelatively elongated con- 0 duit d.

Preferably formed as an integral part of the extension Z is a valvecasing c including a valve seat 7c with which cooperates a valve r, diskZz, secured to the valve body z', which, in 'i turn, is carried by aflexible diaphragm g locked into position by the bonnet member of thevalve casing, which latter is connected by a tubular conduit member fwith the enr larged section of the tubular extension e, be-

- low an ejector or jet nozzle m, which is Athe diaphragm g,

439,719, and in yGermany February 5, 1930. y

formed as an integral portion of the tubular extension e and in axialalignment therewith.

Slidably mounted in the lower chamber a of the casing is a piston valveo, which is normally held out of registry with the tubular conduitmembers Z and Z by means of a frangible washer p, which is secured tothe top of the valve by a screw plug 0', said Washer normally restingupon a shoulder p' formed on the interior Wall of the cylindricall nocasting n.

As thus constituted, the safety device constitutes a return bend in agas conduit between the source of supply, which is connected to thetubular extension Z, and the apparatus to'which the gas is delivered,which is connected to the tubular extension e. In the normal operationof the apparatus, the pressure of the gas, entering the tubularextension Z, causes the diaphragm g to lift the valve from .70 its seatif: permitting the gas to flow freely through the extension Z, chambera, extension Z, coil or conduit d, extension c', chamber I), jet nozzlem, tubular extension e to the torch or other device with which the gasis em- 'I5 ployed. The eiect of the gas pressure passing through the jetnozzle m will be to reduce the pressure or cause a partial vacuum in theenlarged portion of the tubular extension e surrounding the jet nozzle,which reduced pressure is transmitted to the upper side of so that thelatter will be maintained in its elevated position to keep the valvedisk Z0 oif of its seat, so long as the gas pressure in the tubularyextension Z prodominates over that in the upper part of the Valve casingabove the diaphragm. When the device is employed in the supply maindelivering gas, such for example as acetylene, to

one or more blow torches, which latter are also supplied with anothergas, such as oxygen, from a separate source, if the pressure of theoxygen exceeds that of the acetylene, a back iiow of the oxygen isliable to occur, thereby producing an explosive mixture With theacetylene in the tank or reservoir supplying the acetylene. One objectof the instant invention is to prevent this back iiow, which result iseected by the excess pressure due -to the back flow operating on thediaphragm g to overbalance the pressure in the conduit l and to closethe valve carried by the d iaphragm, the predominant back pressure beingtransmitted to the top of the iaphragm by the connectinglconduit finterposed between the tubular extension e and the top of the valvecasing ,abovethe diaphragm. -When once closed, the valve z' will remain1n this position so long. as the bacl; pressure main' tains, but, assoon as suoli back pressure is-re-l lieved and the gaseous mixture isdrawnout of the tubular member e by the operation of theblow torch, thepressure in the upper part of the valve casing will agai conduit` memberl andthe valve will beopened again. As is well known, it is not unusualfor blow torches and likedevices emplo 'ng a mixture of ases, which isnormally exp oslve, to back re with the resultant "dangerof causingexplosion of the gases in the tanks or reservoirs supplying such torcheso r like devices. To prevent 'the effect of the back lire or explosionreaching the source of g5. supply of gas to the device, the other safetyelement of the apparatus is provided, that is to say, the piston valveo,which, asstated, isnormally supported in ippperative position by thefrangi le rinp. a0., pressure developed y th'e U plosion reaches thechamber b, it (is imposed directly upon the top ofthe piston valve 'andruptures the fran'glble ring-p, so that the piston J valve is'forceddownward /into the 35.1ower portion of the chamber a: closing theopenings from the tubularv sections LZ and l',

into said clramber, thereb stopping the flow of gas from the conduit andalso sto ping the advance of the roducts of the "exp osion' orbackfire.As t e speed of travel of the' prductsof the back lire'or 'explosion ishigllll, there is danger .of such products reachin t e n be reduced`below the supply pressure of t e gas` in the en the excessive I back ireor exsections, a valve casin in one section, an ejector nozzle in theadjacent section, a diashragmin said casing, a valve carried by saidiaphragm controlling the flow in said conduit and normally held open bythe line pres- 7n sure on the valve seat of the diaphragm, anda/tubular;k connection between the valve casing on the lopposite side ofthe diaphragm and the conduit section adjacent the ejector nozzle.

3. A safety device for gas lines, comprising `a conduit' havingadjacetsections, a diaphragm operated valve in one section effective tostop the How of gas when back pressure occurs inthe othersection, acasing connecting the adjacent sections, a piston valve go in the lowerpart of said casing to prevent flow in either direction 'through saidcasing, and frangrible means for retaining the piston valve in openrelation but rupturable underexcess pressure to release the valve. 4. Asafety device for gas lines, comprising a casing having inlet and outletconnections near both the top and bottom thereof ands adapted to beinterposed in adjacent sections; of a return bend conduit, apiston valveinlsaid;V 9i! casing adapted to stop the flow in one sectionl of saidconduit, and a frangible means for, supporting said valve in inoperativerelation; in said casing, said means being rupturable under excessivepressure to release the valve. 5. A safety device for gas lines,comprising' a casing having inlet and outlet connections near both thetop and bottomthereof, and a shoulder on its in ner wall intermediateitsV length, a piston valve slidablein the lower part of said casing toopen. and close the lower. inlet and outlet connections, and afrangible, ring fixed to the' piston and engaging the. shoulder in thecasing to hold the piston in inoperative position, said, ring beingrupturv IGI) j able under excess pressure to release the valve.

FRANCESCO MANGrIAMELI.

source of supply of the gas to the con uit l' before the piston valvecan close and in order `,to avoid t s contingency, the conduitconnecting the tubular. extension Z 'and e is made of considerablelength and preferably in coil or helical form to retard the progress -ofthe products of the back fire orA explosion, `thereby affording ampletime for the'piston valve o to close.

What I claim is 1. A safety device for gas lines, comprising a conduithaving adjacent sections, a da- 55 phragm operated valve in one sectionfor controlling the iow in said conduit, an ejector nozzle in theadjacent section, and, a tubula'r connection between the diaphragm valveand the adjacent section near said nozzle; where- 60 by reduction ofpressure by the nozzle will maintain the valve open, and back ressure inthe conduit adjacent the nozzle will operate the diaphragm to close thevalve.

2. A safety device for gas lines, com rising 5 a conduit having a returnbend with a jacent

